Dinuclear iron(III) complexes with different ligation for ring opening polymerization of lactide

Dimeric iron(III) complexes bearing acetylacetonate (acac) ligands and tridentate chiral Schiff base ligands, which were synthesized from condensation reactions between salicylaldehyde and amino-indanol, were prepared and characterized by various methods, including infrared spectroscopy and mass spectrometry. X-ray analysis revealed that two iron centers are each coordinated octahedrally within the complexes, but are situated in different coordination environments; one is attached to two tridentate ligands with meridional isomerization, while the other is coordinated to two acac molecules and two of the oxygen atoms of the indanol moieties of the Schiff bases. The complexes showed higher activity than Fe(acac)3 for the ring opening polymerization of lactide.